First principles simulation of the stimulated Raman spectrum of CuBi₂O₄

CuBi₂O₄ is an emerging p-type semiconductor for applications as a photocathode in photoelectrochemical (PEC) solar fuel production. Recently, we have examined p-CuBi₂O₄ thin films with a comprehensive spectroscopic and first principles characterization methodology to describe its fundamental electronic and optical properties while addressing intrinsic limitations in the observed PEC performance [1, 2]. In this talk, we establish connections between electronic structure, vibrational properties, and PEC performance through a combination of Raman spectroscopy and density functional theory (DFT) modeling. Our computed Raman spectrum for pristine CuBi₂O₄ is in excellent agreement with experimental results. Furthermore, we investigate the stimulated Raman spectrum of CuBi₂O₄ using DFT methods by obtaining the Raman spectrum of a supercell structure with a localized electron polaron, a quasi-particle formed by an electron and its self-interaction with a local lattice distortion. Our results reveal carrier relaxation pathways and provide a methodological approach to study femtosecond stimulated Raman spectra of semiconductors from first principles. References: [1] J. K. Cooper et al., Chem. Mater. 33, 934 (2021); [2] Z. Zhang et al., Chem. Mater. 33, 7829 (2021).